This application claims the priority benefit of Taiwan application serial no. 88109771, filed Jun. 11, 1999.
1. Field of Invention
The present invention relates to a voltage converter. More particularly, the present invention relates to a voltage converter for a suspension-to-RAM (STR) mode of power management in a computer system.
2. Description of Related Art
Ever since the ATX specification for a personal computer was introduced by Intel Corporation of America, power supply has no longer been a passively switched power provider for a computer system. Thereafter, Intel, Microsoft and Toshiba together introduced the advanced configuration and power interface (ACPI) specification that provides four idle states representing the level of tasks for a computer system. Depending on the amount of tasks for a computer system, energy can be saved by suspending power from some of the devices. In the ACPI specification, according to the amount of tasks from small to large, the suspension idle modes provide 4 states: S1/S2 states, power-on suspend; S3 state, suspending to RAM (STR); S4 state, suspending to disk; and, S5 state , mechanical off. When it is suspended to RAM, all other clock pulses except the real-time clock on the main circuit board are stopped temporarily. Under such circumstances, the CPU and other electric circuit will stop working due to the absence of electrical power.
An apparatus for efficiently providing appropriate level of voltage to the system memory of a computer when the computer enters/recoveries to/from STR mode is currently being actively research.
Accordingly, the object of the present invention is to provide a voltage converter for a suspension-to-RAM (STR) mode of power management in a computer system. The voltage converter is capable of supplying a correct voltage to a system memory according to the mode of power management.
A second object of the invention is to provide a voltage converter for the STR mode of power management. The voltage converter is capable of changing the voltage applied to the system memory according to whether the computer system is in the STR mode or the normal mode.
A third object of the invention is to provide a voltage converter for the STR mode of power management. The voltage converter is integrated within a single chip such that the converter is able to transmit data to or from a control chipset via a bus.
To achieve these and other advantages and in accordance with the purpose of the invention, as embodied and broadly described herein, the invention provides a voltage converter. The voltage converter comprises a flip-flop, a resume and initialization logic circuit for producing a resume signal, a STR logic circuit for producing a STR signal, a first voltage-conversion unit and a second voltage-conversion unit. An output terminal of the resume and initialization logic circuit is connected to a first input terminal of the flip-flop. An output terminal of the STR logic circuit is connected to a second input terminal of the flip-flop. An output terminal of the flip-flop is connected to the first voltage-conversion unit. When the resume signal is at a low level and the STR signal is at a high level, the system memory voltage VDIMM is changed to a suspension voltage VSUS. A complementary output terminal of the flip-flop is connected to the second voltage-conversion unit. When the resume signal is at a high level and the STR signal is at a low level, the system memory voltage VDIMM reverts to a power voltage VCC.
The invention also provides a voltage converter control chip capable of implementing a STR mode of power management in a computer system. The voltage converter control chip comprises a bus interface, a controller, a logic control circuit, a first voltage-conversion unit and a second voltage-conversion unit. The bus interface is connected to the control chipset through a bus. The controller has a first and a second output terminal. The controller is connected to the bus interface. The logic control circuit has a first and a second output terminal. The logic control circuit is used as a logic circuit for switching into or out of a STR mode of power management. The first voltage-conversion unit is connected to the logic control circuit and a first output terminal of the controller via a first logic gate. An input terminal of the first voltage-conversion unit is connected to a suspension voltage VSUS. An output terminal of the first voltage-conversion unit is connected to a voltage pin VDIMM of the system memory. Similarly, the second voltage-conversion unit is connected to the logic control circuit and a second output terminal of the controller via a second logic gate. An input terminal of the second voltage-conversion unit is connected to a power voltage VCC. An output terminal of the second voltage-conversion unit is connected to the voltage pin VDIMM of the system memory. To switch the computer system into the STR mode of power management, the first voltage-conversion unit is turned on while the second voltage-conversion unit is turn off according to the output control signals of the logic control circuit. Hence, the suspension voltage VSUS is output to the system memory pin VDIMM, and the STR mode of power management is activated. To switch the computer system back from the STR mode of power management, the first voltage-conversion unit is turned off while the second voltage-conversion unit is turned on according to the output control signals of the logic control circuit. Hence, the source voltage VCC is output to the system memory pin VDIMM, and the computer is resumed to power-on state.
The first voltage-conversion unit can be implemented using a P-channel metal-oxide-semiconductor field effect transistor (PMOSFET). The source of the PMOSFET is connected to a suspension voltage VSUS and the drain is connected to the voltage pin VDIMM of the system memory. The second voltage-conversion unit can be implemented using an N-channel metal-oxide-semiconductor field effect transistor (NMOSFET). The source of the NMOSFET is connected to a source voltage VCC and the drain is connected to the voltage pin VDIMM of the system memory.
In short, the voltage converter or the voltage converter control chip that supports the STR mode of power management in a computer comprises simple logic circuits and MOSFET transistors. It is to be understood that both the foregoing general description and the following detailed description are exemplary, and are intended to provide further explanation of the invention as claimed.